This thesis comprises three main sections: a literature review, research report, and a critical appraisal of the research process. The literature reviewed is the existing research relating to trust as a construct. An attempt is made to clarify the conceptual confusion that exists in the area, by suggesting a comprehensive definition of what is meant by the term trust for the purposes of both the current study and future research. The importance of trust in relation to mental health and therapeutic relationships is discussed. Current measures of the construct are critically examined, and the ‘scientist’ versus ‘humanist’ divide is explored. It is concluded that a new multidimensional trust measure is required to further research efforts in the area. The aim of the research project was to develop a trust measure to form a part of a larger endeavour to operationalise the concept of mental health via key set of basic human emotions and responses. The research reported in Section 2 consists of a Pilot Test, Main Study, and follow up validation study of a new multidimensional measure of trust. Three bases of trust were hypothesised and tested. These were: self trust, interpersonal trust, and environmental trust (that is, trust in wider social, cultural, or political context). A new measure was constructed and validity tested using an inductive approach, and the relationship between trust and trait anxiety was also examined. The results supported the hypothesis that trust is a multidimensional construct, and demonstrated a strong relationship between trust and trait anxiety. It is hoped that this work will rekindle research interest in this important area. The final section is the researcher’s critical appraisal of the research process based on her personal research diary. It is a reflective piece that examines the impact of the research on the researcher (and vice versa) and the critical events in the research process.